Subdural haemorrhages: bilateral acute on chronic

Case contributed by Ms Michelle Leung


Patient with known ischaemic heart disease and coronary stent insertion presents to ED post headstrike with nil loss of consciousness. No headache. GCS 15.

Patient Data

Age: 75 years
Gender: Male

First presentation (post initial fall)

There are two large bilateral subdural haemorrhages of maximal thickness 19 mm on the right and 23 mm on the left. The subdural haemorrhages extend the length of the cerebral hemispheres. There is sedimentation layering reflecting acute on chronic subdural haemorrhage. There is no midline shift.


Second presentation (unconscious collapse a month and a half after fall and surgery)

There are small to moderate size bilateral acute on chronic subdural haematomas. The largest on the left measures up to 11 mm. The one on the right measures up to 5 mm. These have decreased in size significantly since previous. No midline shift or mass effect is seen. 

Case Discussion

The radiographic appearance of an acute on chronic subdural haemorrhage may vary depending on the type of re-bleed and the organization of chronic bleed. 

It may appear isodense to the brain tissue, as a small acute bleed will mix with the lucent fluid of the chronic haemorrhage. Repeated trauma with active bleeding will cause a clot to form and would appear as a hyperdense lump within hypodense haemorrhage. It may also have a layered or ‘sedimentation appearance’. This is caused by the separation of extra-axial fluids of varying densities by internal membranes within the chronic clot. 

As illustrated in the case study, the layered appearance of various blood components are separated by the internal membranes and gravity on the left. Contralaterally, a gradation from the chronic bleed anteriorly to the acute bleed posteriorly in the parietal parts of the skull is seen. This is due to the higher density of the acute bleed and supine position.

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Case information

rID: 54062
Published: 12th Oct 2017
Last edited: 12th Oct 2017
Inclusion in quiz mode: Excluded

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